When I import uncompressed avi (1080/60i, 16:9) or Cineform's semi compressed avi for burning to avchd disk, it comes out as 4:3 with no way to change it (aspect ratio option grayed out).
It plays in Nero showtime as 16:9 prior to import so I know it originates as 16:9. (It also imports back into Sony Vegas as 16:9)
